/*
2. Add Two Numbers  
Total Accepted: 139504 Total Submissions: 605991 Difficulty: Medium

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

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*/


/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode *ret = NULL;
        ListNode **pret = &ret;
        int val = 0;
        int ist = 0;
        while(l1){
            
            if (l2){
                val = l1->val + l2->val + ist;
                l2 = l2->next;
            } else {
                val = l1->val + ist;
            }
            l1 = l1->next;
            *pret = new ListNode(val%10);
            pret = &(*pret)->next;
            ist = val/10;
        }
        while(l2){
            val = l2->val + ist;
            l2 = l2->next;
            *pret = new ListNode(val%10);
            pret = &(*pret)->next;
            ist = val/10;
        }
        if (ist){
            *pret = new ListNode(ist);
            pret = &(*pret)->next;
        }
        return ret;
    }
};

